Bias relieved automatic seat return

ABSTRACT

This disclosure relates to an improved support for a seat having a stationary standard, an arm pivotally mounted at one of its ends on the standard, and a seat member mounted on the other end of the arm. The improved structure disclosed has a biasing element shiftable between operative and inoperative positions. When in an operative position, the biasing element urges the arm to pivot in one direction about the standard to assume a storage position. In response to the weight of a person on the seat member, the biasing element is rendered inoperative, and the arm becomes freely movable about the support.

United States Tatent 1 Ostertag [54] BIAS RELIEVED AUTOMATIC SEAT RETURN [75] Inventor: Hubert L. Ostertag, Holland, Mich. [73] Assignee: Herman Miller, Inc., Zeeland, Mich.

[22] Filed: March 3, 1971 [21] Appl. No.: 120,400

[52] U.S. Cl. ..297/142, 297/349, 248/417 0 [51] Int. Cl ..A47c 3/18 [58] Field of Search ..297/142, 331, 332, 334, 349, 297/240, 241, 242; 248/417, 145

[451 Jan. 9, 1973 Primary Examiner-Francis K. Zugel Attorney-Price, Heneveld, Huizenga & Cooper [57] ABSTRACT This disclosure relates to an improved support for a seat having a stationary standard, an arm pivotally mounted at one of its ends on the standard, and a seat member mounted on the other end of the arm. The improved structure disclosed has a biasing element shiftable between operative and inoperative positions. When in an operative position, the biasing element urges the arm to pivot in one direction about the standard to assume a storage position. In response to the weight of a person on the seat member, the biasing element is rendered inoperative, and the arm becomes freely movable about the support.

14 Claims, 9 Drawing Figures PATENTEUJAN 9191a 3.709.555

sum 1 or 3 34 v o INVENTOR HUBERT L. OSTERTAG FIG. 3

BY 77M W ATTORNEYS PATENTEDJAN sum 3.709.555

' SHEET20F3 v k m k. 62 w fiar N" 7 EiS jm 2E 5 e2 50 =E EKG-:5 4 as FIG. 5

INVENTOR HUBERT L. OSTERTAG ATTORNEYS PAIENTEDJMI 9 ma SHEEI 3 0F 3 FIG.

INVENTOR HUBERT' L. OSTERTAG ATTORNEYS BACKGROUND OF THE INVENTION This invention relates to improvements in automatic seat return structures for cantilevered furniture. In this type structure, a seat member is rotatably supported on a cantilevered arm member which is in turn pivotally supported on a fixed support member. Spring biasing means are provided so that when the seat is unoccupied the seat and the cantilevered member are biased into a storage position.

An example of this type structure is shown in US. Pat. No. 3,535,000, entitled Cantilevered Furniture and Joints Therefor, issued Oct. 20, 1970, and assigned to the assignee of the present invention. This patent teaches a combination seat and table structure wherein the seat is mounted on a double-jointed structure for both swinging pivotal movement about a main support post and for rotation about the center of the chair. When not in use, the seat is automatically biased into storage position adjacent to and with its back parallel with the table.

In the above-described structure, separate biasing means are provided at both the connection between the seat and the cantilevered arm and at the joint between the arm and the main support post. When in use, the biasing means constantly urges the structure toward a storage position requiring the individual seated thereon be constantly exerting a counterforce to overcome the spring bias. This, over a long period of time, can become not only tiring but also distracting. When utilized in a classroom, small children often find it amusing to raise their feet from the floor and ride the biased chair toward a closed position. This too is distracting not only to the individual but to other members of the group.

SUMMARY OF THE INVENTION In view of the above-mentioned problems which are inherent in the prior art, resiliently biased, furniture constructions, I have now provided an apparatus wherein the automatic seat return mechanism is rendered inoperative while the seat is occupied and is automatically rendered operative to return the seat to a storage position when the seat is unoccupied.

OBJECTS OF THE INVENTION By various aspects of this invention, one or more of the following, or other, objects can be obtained.

It is an object of the present inventionto provide a spring biased support for cantilevered chair structure wherein the seat will automatically return to storage position when not in use.

It is a further object of the present invention to provide a chair support wherein the seat is freely rotatable I when moved away from a storage position.

It is another object of the present invention to provide a cantilevered chair support wherein the seat is This is accomplished in an apparatus wherein a seat is supported on a cantilevered arm such that the arm is pivotable relative to a support and the seat is rotatably supported on the cantilevered arm. The connection between the arm and its support comprises a bracket and a vertical pin on the support and a housing on the am which is pivotably supported on the pin. The pin and the housing contain rotation limiting means to limit the extent of relative rotation between the bracket and the housing.

The seat is rotatably supported on a swivel shaft in the cantilevered arm and contains a means to bias the seat in a predetermined position with respect to the cantilevered arm. The biasing means is such that the seat is free to rotate through a limited angle when the seat is pulled away from a storage position. The biasing means is further arranged so that when the seat is occupied the bias is automatically removed and the seat and the cantilevered arm are rendered freely movable through a limited angle.

freely rotatable on its support when occupied, but which will return to a given positionwhen it is unoccupied.

It is another object of this invention to provide a biased cantilevered seat assembly wherein a single biasing means provides a bias for the rotatable seat and also for the pivoted cantilever arm.

It is still a further object of this invention to provide a cantilevered seat assembly wherein the seat is freely rotatable about its cantilevered support when it is occupied, but which returns to a given position relative to the support when it is unoccupied.

' It is yet another object of the present invention to provide a cantilevered seat assembly wherein when the seat is rotated from a central position, the bias is automatically removed from the cantilevered support structure.

Other aspects, objects, and many advantages of this invention will become apparent to one skilled in the art from a study of this disclosure, the drawings, and the appended claims.

The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a side elevational view of an embodiment of the invention;

FIG. 2 is a top plan view of the invention showing both the storage and operating rotational positions of the seats;

FIG. 3 is a fragmentary, enlarged, elevational view of the supporting mechanism taken along plane 3-3 of mechanism of the invention with the cam follower and shaft shown in phantom for clarity;

FIG. 8 is a cross-sectional view taken along plane 8- 8 of FIG. 7 showing the cam mechanism in a rotated position; and

FIG. 9 is a cross-sectional view taken along plane 9- 9 of FIG. 8 showing the rotation limiting means for the seat support shaft.

view taken along plane 44 of I DESCRIPTION OF THE PREFERRED EMBODIMENT While my invention is applicable to one or a plurality of cantilevered seat structures, for convenience, my invention will be described with reference to a pair of seats; one shown in a closed or storage position, while the other is shown in an open or occupied position.

Referring now to the drawings, and particularly to FIGS. 1 and 2, a seating construction embodying the novel structure of my invention is generally indicated by the numeral 10. There is provided a desk top 12 at which are positioned seats 14. A support post 16 supports the seats 14 through a cantilevered arm 18 and also supports the desk top 12. A bracket attached to the post support member 16 rotatably supports cantilevered arm 18. The cantilevered arm 18 is rotatable about a point on the support post. The seat 14 is rotatably mounted on the opposite end of each of the cantilevered arms 18.

The supporting post 16 has a rectangular flange 17 attached to the bottom thereof. The flange 17 may be rigidly attached to the floor structure by any suitable fastening means. The table top supporting structure is a substantially vertical supporting bracket 13 fixed to the post at the upper portion thereof and extending beneath and attached to the table top 12. This structure does not form any part of the invention, and any other arrangement can be utilized with this invention.

In the present invention, as well as in the abovedescribed prior art US. Pat. No. 3,535,000, a means is provided to bias the seats 14 and cantilevered arms 18 such that the seats are urged forwardly toward the desk top 12. Means are provided to so limit the rotational movement of the cantilevered arms 18 towards the table that the seat will strike the desk top. On the cantilevered arm 18, there is an additional means provided to bias the seat so that its back is always parallel to the edge of the table where it assumes its storage position.

cally return to the position shown on the left in FIG. 2,

that is, with the back of the seats close to, but not touching, the desk edge, and with the general plane of the back parallel to the edge of the desk. In a room where multiple seats are employed, an orderly appearance will prevail without the need for individually straightening the seats. Also, this prevents damage resulting from contact between the seats and the desk- In the prior art structure above-described, individual spring biasing means are provided at the connection of the arm 18 with the support post 16 and also at the connection of seat 14 with the cantilevered arm.

Turning now to FIG. 3, the improved structure of my invention will be described in detail. The left side of the figure depicts the seat structure in an unoccupied or storage position, while the right side depicts the occupied, freely movable position of the seat and cantilevered arm.

The support post 16 and bracket 20 are shown rotatably holding the cantilevered arm 18. At the opposite ends of the arm 18, a shaft 22 or movable element is rotatably supported in a housing 24 formed at the end of the arm 18. As shown in FIG. 1, the shaft 22 is fixed to a seat support 26 which is secured to the lower surface of the seat 14. The rotatable shaft 22 is also mounted for vertical movement within housing 24 and has a collar 28 rigidly secured to or formed integral therewith to limit its downward vertical movement within the housing. The collar 28 further provides a bearing surface between the housing and the seat assembly when the seat is occupied and rotated.

A detailed sectional view of the joint between the cantilevered arm 18 and the mounting bracket 20 on support post 16 is illustrated in FIG. 5. A pivot shaft or pin 30 is fixed between an upper flange 32 and a lower flange 34 of bracket 20 by mounting screws or dowels 36, passing through the flanges into the pin. To prevent rotation of the pin with respect to the mounting bracket flanges 32 and 34, one of the dowels 36 may be located slightly off center. Other means of preventing such relative rotation will immediately become obvious to one skilled in the art.

The rotational freedom of arm 18 about pin 30 is fixed within certain limits by a travel limiting mechanism machined into the pin and cast into the housing 38 which is formed on the end of the cantilevered arm 18. A sectional view of the travel limiting mechanism is shown in detail in FIG. 6. The pin 30 has a recess 40 in its outer periphery extending a predetermined angular distance. The housing 38 of the cantilevered arm 18 is provided with a protruding finger or stop 42 adapted to seat and move within the recess 40 of the pin. In practice, it has been found desirable to limit the travel of the arm to approximately 7 0 degrees or about 35 degrees either side of a line drawn through the center of the pin and parallel with the desk top surface 12.

Referring again to FIG. 5 and additionally to FIGS. 7 through 9, the seat support shaft 22, its rotational limiting means, and the seat and arm biasing means will be described in detail. As previously mentioned, the seat support shaft 22 is a movable element mounted for rotational and vertical movement within housing 24 on the end of cantilevered arm 18. The collar 28 limits the vertical downward travel of the shaft within the hous- As best illustrated in FIGS. 7, 8, and 9, the rotation of the seat support shaft 22 is limited by a cam surface 48 which is machined on the inner surface of housing 24. A cam follower 46 fixed on support shaft 22 contacts the cam surface and limits the rotation of the support shaft which in turn limits the rotation of the seat.

The cam surface 48 machined in the housing 24' is comprised of sections 49, 50, 52, 54, and 55. When the cam follower 46 is positioned at apex or point 52, the seat will be positioned suchthat theback ofthe seat will be parallel to the edge of the table. As the seat is turned, for example, in a clockwise direction as viewed in FIG. 2, the cam follower 46 will move along the cam surface 54 until it reaches stop 49 which acts as a positive limit and prevents further rotation in that direction. At the same time, the seat and shaft are forced downwardly until the collar 28 rides on the top surface of the housing 24. Conversely, as the seat is rotated in a counterclockwise direction as viewed in FIG. 4, the cam follower 49 will move along the cam surface 50 until it reaches the opposite stop 55. Preferably, the total angle of rotation is about 180 between stop 49 and stop 55, or approximately on either side of the apex 52.

When the seat is unoccupied, the shaft 22 is constantly biased upwardly into an operative position by a bias spring 60 so that the cam follower 46 is at apex 52 on the cam surface. The spring 60 is contained within the housing 24 (FIG. 5).

When the chair is occupied, as shown in the right hand side of FIG. 5, the spring 60 is compressed to an inoperative position by the downward movement of the shaft 22. In this position, the cam follower 46 will move away from the cam surfaces, permitting unrestrained rotation of the seat between the limits prescribed by stops 49 and 55.

A flat disk 62 having a hole in its center is positioned between the lower end of shaft 22 and the spring 60. A retaining washer 64 is fixed in the bottom surface of the housing 24 and serves to hold the spring 60 against the disk 62. The retaining washer may be held in place by dowel pins (not shown) or may be threadably received in the housing to provide a convenient means of adjusting the amount of bias applied on the shaft 22 by spring 60. A guide member 68 having a hole in the center is provided in the center of the retaining washer.

A cable 70, preferably a multi-strand metallic cable is equipped at one end with an enlarged terminal 72. The terminal 72 is seated in a recess 74 formed in the lower end of the shaft 22 and bears against the top of the disk 62. The other end of the cable 70 is passed through the hole in the disk 62, through the spring 60, and through the guide member 68 in retaining washers 64. Alternately, the cable may be fixed directly to the shaft 22 in any convenient fashion, thereby eliminating the disk 62.

Referring now to FIG. 4, the pin 30 and support arms 18 are shown in cross section. A counter-bored hole 78 is provided through each of the pins 30 across a cord thereof. The cable 70 is passed through counter-bored hole in the pin and is secured at its end in the counterbored portion by a terminal fitting 80. The path of the cable as it enters the hole 78 is bent when the seat is in a storage position (see left side of FIG. 4). When the seat is in extended or operating position, the cable is partially wrapped around the pin 30 (see right side of FIG. 4). Where the cable passes into the socket seating the pin 30, it is threaded through a guide 82. For convenience in installation, the cable may consist of two portions84 and 84a joined by a compression fitting 86 midway along the length of the arm 18.

When a seat is unoccupied, as shown in the left-hand side of FIG. 5, the spring 60 biases the shaft 22 rotatably upwardly into operative position while the cam follower 46 rides along the cam surface sides 50 and 54 of the cam surface 48 until it reaches the apex 52. At this point, the shaft has reached the upper limit of its travel. The upward travel of the shaft 22 places the seat in a predetermined position with respect to the arm 18.

As the shaft 22 is urged upwardly by the bias spring 60, a corresponding force or pull is exerted on the terminal fitting 72 by the disk 62 and as a result, to the cable 70. This force is transmitted through cable 70 to that portion of the cable which is wrapped around and connected to the pin 30. The tension applied by the bias spring 60 causes the arm 18 to rotate about the pin 30 because the cable, to obtain the added length necessary for the disk 62 to follow the shaft 22 upwardly unwraps the cable from the pin 30 by bearing against the into a storage position with the back of the seat in line with and parallel to the desk top. The cam follower 46 on shaft 22, spring 60, and cam surface 48 form a cooperative biasing element which in an operative position, i.e., when cam follower 46 is biasedupwardly by spring 60 into the apex 52 of cam surface 48, returns the seat and the arm (through cable to a predetermined storage position.

The occupied position of the seat is shown in the right-hand side of FIG. 5. When the seat is occupied, the shaft 22 is moved downwardly against the bias spring 60 until the collar 28 contacts the top surface of the housing 24.

In this position, all tension is released from the cable 70, and all bias with respect to the rotation of the shaft 22 within the housing 24 has been removed. The biasing element is-in inoperative position thereby allowing the seat structure on the shaft to be freely rotatable within the limits of the stops as shown in FIG. 9. Release of the tension on the cable 70 also relieves the bias provided on the pin 30 with respect to the arm 18. This allows the arm 18 to be freely rotatable on the pin 30 within the limits of the stops detailed in FIG. 6.

The tension on the cable and the bias on the arm 18 with respect to the pin 30 may also be released by rotating the seat structure and shaft 22 to either side of the position attained when the cam follower 46 is at apex 52 on the cam surface. As the cam follower 46 moves along the cam surface sides 50 and 54, the shaft is drawn downwardly against the bias spring placing the biasing element ininoperative position which releases the tension on the cables. However, a minimum tension remains on the cable when the seat is in storage to positively hold the seat in storage.

It may, therefore, be readily seen that I have provided a novel biasing means for cantilevered furniture construction wherein a single bias spring provides a bias for both the seat structure and the arm structure and wherein, when released, the seat and arm will assume a storage position with the seat back parallel to and in alignment with the desk top.

My novel structure further provides a bias releasing means wherein when the seat is either occupied or turned from a predetermined position, the bias on the cantilevered arm with respect to the support structure is released.

Reasonable modifications and variations are possible within the scope of the foregoing disclosure and drawings without departing from the spirit and scope of the invention.

I claim: 7

1. In a support for a seat, a stationary standard, an arm pivotally mounted at one of its ends to said standard, and a seat member mounted on the other end of said arm; the improvement comprising: a movable element pivotally mounting said seat member on said other end of said arm, said movable element being shiftable in response to the weight of a person on said seat member; a biasing element shiftable between operative and inoperative positions, said biasing element when in operative position urging said arm to pivot in one direction about said standard and urging said seat member to pivot about said arm to a predetermined position with respect to said arm; said movable element being operatively connected to said biasing element to shift said biasing element to inoperative position rendering said arm and said seat member freely rotatable when said movable element shifts in response to the weight of a person on said seat member.

2. The support as claimed in claim 1 wherein said biasing element includes a spring seated in said other end of said arm and one end of said movable element rests on said spring.

3. A seat support as claimed in claim 2 wherein said biasing element further includes cooperably engageable cam and cam follower means associated with said spring and said movable element whereby when said biasing element is in an operative position said cam and cam follower urge said seat structure toward said predetermined position with respect to said arm.

4. The seat support as claimed in claim 3 wherein said cam is on one of said other end of said arm and said movable element and said cam follower is on the other.

5. In a support for a seat, a stationary standard, an arm pivotally mounted at one of its ends to said standard, and a seat member mounted on the other end of said arm; the improvement comprising: biasing means, said biasing means being shiftable between operative and inoperative positions; a member connecting one end of said biasing means to said standard, said member biasing said arm to pivot about said standard when said biasing means is in operative position; a movable element connected to said seat member pivotally mounting said seat member to said other end of said arm, said movable member operatively connected to said biasing means to bias said seat to pivot about said other end of said arm when in operative position said movable member shiftable in response to the weight of a person on said seat member for shifting said biasing means to inoperative position to thereby remove the bias on said arm about said standard and said seat about said other end of said arm in response to the presence of a person on said seat member.

6. The support described in claim 5 wherein said biasing means includes a spring seated in said other end of said arm and one end of said movable element rests upon the top of said spring the other end of said movable element being connected to said seat member.

7. The support described in claim 6 and further including means urging said movable element and said seat toward a predetermined position with respect to said arm when said biasing means is in an operative position.

8. The support as claimed in claim 7 wherein said urging means is a cam surface in said other end of said arm and a cam follower on said movable element, said cam follower adapted to follow said cam surface when said biasing means shifts from inoperative to operative position.

9. In a support for a seat, a stationary standard, an

arm pivotally mounted at one of its ends to said standard, and a seat member mounted on the other end of said arm; the improvement comprising: a biasing element shiftable between operative and inoperative positrons, said blasmg element when in operative position urging said arm to pivot in one direction about said standard; support means pivotally mounting said seat member on said other end of said arm, said support means operatively connected to said biasing element and rendering said biasing element inoperative when said seatmember isturned from a predetermined position whereby said arm is freely rotatable about said standard.

TIT A releasable biasing mechanism for a cantilevered seat construction comprising: a stationary support member; mounting means on said support member; an arm pivotally mounted at one of its ends on said mounting means; a shaft rotatably mounted in the other end of said arm and adapted to support a seat structure; earn and cam follower means in said arm associated with said shaft; means biasing said shaft into a position determined by said cam and said cam follower means; means connecting said biasing means and said mounting means to effect a bias on said arm with respect to said stationary support when said shaft is biased into said position; and means responsive to movement of said shaft from said position to release the bias on said shaft and said arm whereby said shaft and said arm are freely rotatable.

11. A biasing mechanism as claimed in claim 10 wherein said cam is formed in the inner diameter of a housing formed at said other end of said arm and said cam follower is fixed on said shaft.

12. A biasing mechanism as claimed in claim 10 wherein said connecting means is a cable fixed at one end to said shaft and at its other end wrapped partially around and fixed to said mounting means whereby in response to movement of said shaft from said position said cable is partially unwrapped from said mounting means as said arm is moved therearound.

13. A biasing mechanism as claimed in claim 11 and further including rotation limiting means on. said mounting means and on said shaft.

14. A biased support for a seat structure comprising: a stationary support member; a mounting pin on said support member; an arm pivotally mounted at one of its ends on said mounting pin; a shaft rotatably mounted in the other end of said arm and adapted to support a seat structure; a cam and cam follower in said arm associated with said shaft, said cam formed in said am and said cam follower fixed on said shaft; a bias spring in said arm below said shaft biasing said shaft into an operative position determined by said cam and cam follower, said shaft shiftable against said bias spring to an inoperative position in response to the weight of a person on said seat structure; and a cable member connecting said shaft to said mounting pin to effect a bias on said arm with respect to said stationary support member when said shaft is biased to an operative position to thereby move said arm to a storage position. 

1. In a support for a seat, a stationary standard, an arm pivotally mounted at one of its ends to said standard, and a seat member mounted on the other end of said arm; the improvement comprising: a movable element pivotally mounting said seat member on said other end of said arm, said movable element being shiftable in response to the weight of a person on said seat member; a biasing element shiftable between operative and inoperative positions, said biasing element when in operative position urging said arm to pivot in one direction about said standard and urging said seat member to pivot about said arm to a predetermined position with respect to said arm; said movable element being operatively connected to said biasing element to shift said biasing element to inoperative position rendering said arm and said seat member freely rotatable when said movable element shifts in response to the weight of a person on said seat member.
 2. The support as claimed in claim 1 wherein said biasing element includes a spring seated in said other end of said arm and one end of said movable element rests on said spring.
 3. A seat support as claimed in claim 2 wherein said biasing element further includes cooperably engageable cam and cam follower means associated with said spring and said movable element whereby when said biasing element is in an operative position said cam and cam follower urge said seat structure toward said predetermined position with respect to said arm.
 4. The seat support as claimed in claim 3 wherein said cam is on one of said other end of said arm and said movable element and said cam follower is on the other.
 5. In a support for a seat, a stationary standard, an arm pivotally mounted at one of its ends to said standard, and a seat member mounted on the other end of said arm; the improvement comprising: biasing means, said biasing means being shiftable between operative and inoperative positions; a member connecting one end of said biasing means to said standard, said member biasing said arm to pivot about said standard when said biasing means is in operative position; a movable element connected to said seat member pivotally mounting said seat member to said other end of said arm, said movable member operatively connected to said biasing means to bias said seat to pivot about said other end of said arm when in operative position said movable member shiftable in response to the weight of a person on said seat member for shifting said biasing means to inoperative position to thereby remove the bias on said arm about said standard and said seat about said other end of said arm in response to the presence of a person on said seat member.
 6. The support described in claim 5 wherein said biasing means includes a spring seated in said other end of said arm and one end of said movable element rests upon the top of said spring the other end of said movable element being connected to said seat member.
 7. The support described in claim 6 and further including means urging said movable element and said seat toward a predetermined position with respect to said arm when said biasing means is in an operative position.
 8. The support as claimed in claim 7 wherein said urging means is a cam surface in said other end of said arm and a cam follower on said movable element, said cam follower adapted to follow said cam surface when said biasing means shifts from inoperative to operative position.
 9. In a support for a seat, a stationary standard, an arm pivotally mounted at one of its ends to said standard, and a seat member mounted on the other end of said arm; the improvement comprising: a biasing element shiftable between operative and inoperative poSitions, said biasing element when in operative position urging said arm to pivot in one direction about said standard; support means pivotally mounting said seat member on said other end of said arm, said support means operatively connected to said biasing element and rendering said biasing element inoperative when said seat member is turned from a predetermined position whereby said arm is freely rotatable about said standard.
 11. A biasing mechanism as claimed in claim 10 wherein said cam is formed in the inner diameter of a housing formed at said other end of said arm and said cam follower is fixed on said shaft.
 11. A releasable biasing mechanism for a cantilevered seat construction comprising: a stationary support member; mounting means on said support member; an arm pivotally mounted at one of its ends on said mounting means; a shaft rotatably mounted in the other end of said arm and adapted to support a seat structure; cam and cam follower means in said arm associated with said shaft; means biasing said shaft into a position determined by said cam and said cam follower means; means connecting said biasing means and said mounting means to effect a bias on said arm with respect to said stationary support when said shaft is biased into said position; and means responsive to movement of said shaft from said position to release the bias on said shaft and said arm whereby said shaft and said arm are freely rotatable.
 12. A biasing mechanism as claimed in claim 10 wherein said connecting means is a cable fixed at one end to said shaft and at its other end wrapped partially around and fixed to said mounting means whereby in response to movement of said shaft from said position said cable is partially unwrapped from said mounting means as said arm is moved therearound.
 13. A biasing mechanism as claimed in claim 11 and further including rotation limiting means on said mounting means and on said shaft.
 14. A biased support for a seat structure comprising: a stationary support member; a mounting pin on said support member; an arm pivotally mounted at one of its ends on said mounting pin; a shaft rotatably mounted in the other end of said arm and adapted to support a seat structure; a cam and cam follower in said arm associated with said shaft, said cam formed in said arm and said cam follower fixed on said shaft; a bias spring in said arm below said shaft biasing said shaft into an operative position determined by said cam and cam follower, said shaft shiftable against said bias spring to an inoperative position in response to the weight of a person on said seat structure; and a cable member connecting said shaft to said mounting pin to effect a bias on said arm with respect to said stationary support member when said shaft is biased to an operative position to thereby move said arm to a storage position. 